DeviceNet is a communication protocol employed in the automation industry for interconnecting control devices for data exchange. It is mainly used as a communication network between industrial I/O devices and controllers like limit switches, photoelectric sensors, valve manifolds, motor starters, process sensors, bar code readers, variable frequency drives, panel displays and operator interfaces. Controller Area Network is its backbone technology and an application layer covering a range of device profiles is defined by DeviceNet. Typical applications include
- Information exchange
- Safety devices
- Large I/O control networks
Technical Features
DeviceNet includes following main features:- It defines the Media, Physical, Data-Link, and Application layers of the ISO/OSI 7-layer model.
- On the lower layers i.e. OSI layer 1 to 4, DeviceNet fundamentally uses the CAN specifications with some constraints and extensions while on the upper layers i.e. OSI layer 5 to 7 DeviceNet uses the Common Industrial Protocol (CIP) specified by the ODVA.
- It uses the CAN data frame for information exchange.
- It also adds in trunk line topology with separate buses for signal and power. Usual configuration is two twisted pairs and a single shield.
- Defined Baud rates are 125 kbit/s, 250 kbit/s and 500 kbit/s.
- Trunk length is inversely proportional to the speed, i.e. 500, 250 and 100 meters respectively.
- Use of the quick-fix connector was allowed by adding on a new flat cable to the specification.
- It can support up to 64 nodes on a single logical network. Node addresses range from 0 - 63
- It supports master/slave as well as peer-to-peer communication, though majority of the devices work in the master/slave configuration.
- It allows several masters on a single logical network.
- Network cable can supply device power along same cable as communication cable.
- Networked devices can be both controlled and configured at the same time.
- It has the potential to withstand noisy environments.
No comments:
Post a Comment